As is known, the polymeric substances are generally subject to degradation, such as discoloration and embrittlement, caused by exposure to light, especially to ultraviolet light, and by the action of oxygen and heat.
In order to prevent or delaying such degradation, it is a common technique to add to the polymeric materials various types of compounds opposing such effect, generally referred to as stabilizers.
A particular type of stabilizers which have been very successful are the sterically hindered amines (HAL) and in particular the derivatives of alkyl-substituted piperidine.
Derivatives of alkyl-substituted 4-oxy-4-methyl-piperidine are also known. Thus, e.g., from published European patent application No. 60,559 there are known polymeric products containing, as a repeating unit, alkyl-substituted 4-oxy-4-methylene piperidine, and from Belgian Pat. No. 891,835 there are known alkyl-substituted 4-oxy-4-amino-methyl-piperidines and derivatives thereof containing an alkyl-carbonyl radical or the triazine radical, bound to aminic nitrogen.
Although all these known compounds, containing the 4-oxy-methyl-piperidine radical, are excellent stabilizers for polymeric substances generally subject to deterioration, they are not fit for being utilized, with the same results, in all the polymeric substances and in all the technological uses. In fact, the known stabilizers exhibit the drawback of not possessing all the parameters and characteristics required for all technological appliances, such as low volatility, resistance to migration, thermal stability, insolubility in water, etc.